In recent years, so-called micromachines (MEMS: Micro Electro Mechanical Systems) are becoming widespread. In these machines, various semiconductor elements are mounted on a microfabricated Si substrate (silicon wafer) using LSI manufacturing technology. During the manufacturing of such a micromachine, an electrode that penetrates a Si substrate may be provided. For example, JP-A-2003-328180 discloses a method for providing an electrode that penetrates a substrate. This method includes forming a bottomed via hole in a silicon wafer substrate, filling the bottomed via hole with Cu plating, and grinding the substrate from the surface located opposite from the opening of the bottomed via hole to expose the Cu plating.
In the case where single-wafer etching using plasma is employed as a method for forming a recess such as a bottomed via hole in a Si substrate, the processing cost increases due to the device cost and processing time. Batch etching using a chemical solution can reduce the processing cost. However, this method cannot forma recess having a side surface orthogonal to the Si substrate. For example, it is possible to form a recess in a monocrystal substrate by anisotropic etching from a (100) surface having a crystal orientation of (100). In this case, aside surface of the recess is a (111) surface, and forms an angle of approximately 55° with the (100) surface. When such a recess is filled with Cu plating to form an electrode and the substrate is ground from the surface opposite from the recess, variations occur in the area of the exposed portion of the electrode depending on the degree of grinding.